ARMY TM 10-4610-309-14
MARINE CORPS TM 10802A-14/1
TACTICAL WATER PURIFICATION SYSTEM (TWPS)
DESCRIPTION AND THEORY OF OPERATION
THEORY OF OPERATION
INTRODUCTION
Raw water contains suspended solids, which make it look turbid (cloudy or muddy). Suspended solids
include silt, dirt, small particles, microorganisms, algae, and plant and animal products. Raw water also
contains dissolved solids, which cause poor taste and can make water unfit to drink. The Tactical Water
Purification System (TPWS) removes all suspended solids and reduces the dissolved solids to produce
water that tastes good and is safe to drink. The TWPS can also produce drinking water from seawater
containing high concentrations of salt and freshwater contaminated with nuclear, biological, and chemical
warfare (NBC) agents.
This section provides a detailed theory of operation of the Tactical Water Purification System including:
1. Raw Water System
2. Micro Filtration (MF) System
3. Reverse Osmosis (RO) System
4. Air System
5. Chemical Injection System
6. Standard Product Water Distribution System
7. Extended Product Water Distribution System
8. Nuclear, Chemical, and Biological (NBC) System
9. Operating Controls
10. Power Distribution System
11. Cleaning and Preservation Operations
12. Cold Weather Module
Both the Army A-TWPS and the Marine Corps MC-TWPS versions are set on the ground at the water
point for operation. There are only minor differences in setup and no difference in operation of the TWPS
between the two configurations.
The basic water flow through the TWPS is illustrated in Figure 1. Raw water is pumped from the water
source and into a micro-filter (MF) feed tank. One or two pumps may be used depending on the distance
and elevation change from the source to the MF feed tank. A cyclone separator is used at beach
locations to remove sand and silt. Water is then pumped from the MF feed tank through strainer S-2 to
the micro-filter (MF) assembly. Strainer S-2 removes material larger than 60 microns from the water
stream. The MF assembly removes suspended solids (dirt) and microorganisms down to 0.2 microns.
Filtered water, called "filtrate" flows from the MF assembly into the reverse osmosis (RO) feed tank.
Every 15 minutes a "backwash" operation is automatically performed. The backwash operation forces air
through the MF elements to blow accumulated dirt and material off the filter elements. The dirt is flushed
out of the MF assembly to a waste outlet. Continuing with the water purification process, feed water is
pumped from the RO feed tank to two high-pressure pumps. The high-pressure pumps force some of the
water though membranes in the RO vessels. Salts are rejected by the RO membranes and the water that
passes through the membranes exits the TWPS as product water. The product water is stored in 3000-
gallon tanks. Water that does not pass through the RO membranes is discharged as "reject" water to the
waste outlet. The reject water passes through a turbocharger which transfers energy from the reject
water to boost the feed water pressure to the RO vessels. Product water is pumped from the 3000-gallon
tanks as needed for distribution. Two 3000-gallon tanks are provided with the standard distribution
system. Three additional 3000-gallon tanks and an additional pump are provided with the extended
distribution system.
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